Grain bins have long been used for the drying and storing of grain. Such bins typically include a large containment vessel having cylindrically shaped side walls constructed of galvanized corrugated steel extending upwardly from a base and further having an angled roof sloping upwardly from the upper edge of the side wall. A port will usually be located at the apex of the roof.
This containment vessel will usually be positioned upon a concrete base or platform. A perforated floor will usually be supported within the bin and will be spaced somewhat above the base to form a plenum chamber therebetween.
One or more fans or other air circulation mechanisms will be positioned about the lower periphery of the side wall and will be in pneumatic communication with the plenum chamber. By use of these air circulation mechanisms, air may be forced into the plenum chamber and up through the perforated floor through the grain and then out through the apex port. Conversely, the same system may serve to draw air out of the containment vessel by reversing the air flow.
Air circulation mechanisms such as those referred to above typically include a pneumatic pathway having a motor and fan blade unit mounted therein. One end of the pathway will be pneumatically connected to the grain bin as described above. The remaining end of the pathway will usually be connected to some sort of vent or filter screen.
Usually, the fan blade used in such air circulation mechanisms will not exceed a twelve inch diameter. In consequence, the pneumatic pathways are usually comprised of tubes having an inner diameter of approximately twelve inches as well.
Lately, newer and more efficient fan blades have been introduced. Many of these improved fan blades have a fourteen inch span. The operator of a grain drying installation who wishes to use such improved fan blades must then confront a dilemma. He must either purchase all new ventilation air control equipment to accommodate the new blade, or dramatically modify the existing equipment.
It would be desirable to provide such operators with a way to utilize such new fan blades without making obsolete the ventilation air control units he already has. Such operates could then obtain ventilation air control systems having a higher static pressure in combination with a greater volume of air movement at a reasonable cost.
It should be understood that the dimensions hereinabove stated are illustrative only and that the principles of my invention will apply to any size fan blade and housing smaller and larger.